Provided is a light measuring device having a simple configuration that can reliably detect a small amount of plaque and can be easily incorporated into a toothbrush. The light measurement device includes a plurality of light sources that respectively irradiate the sample with light of a plurality of different wavelengths, a detection unit that detects the intensity of each inspection light generated when the sample is irradiated with light of a plurality of wavelengths, And a control unit that calculates the amount of fluorescent substance to be measured based on the intensity of the inspection light detected by the detection unit corresponding to the light of a plurality of wavelengths.少量の歯垢を確実に検出でき、しかも歯ブラシに容易に組み込むことができるシンプルな構成の光測定装置を提供する。光測定装置は、互いに異なる複数の波長の光をそれぞれ試料に照射する複数の光源と、複数の波長の光を試料に照射したときに発生するそれぞれの検査光の強度を検出する検出部と、複数の波長の光に対応して検出部でそれぞれ検出された検査光の強度に基づいて測定対象の蛍光物質量を演算する制御部とを有する。
